The mother of murdered black teenager Stephen Lawrence said the Government is not doing enough to tackle racism, it has been reported.

Doreen Lawrence told the Guardian ministers could be hugely influential in the battle against prejudice but she has "not heard them talk about race."

Earlier this month Gary Dobson, 36, who is already serving a five-year sentence for drug-dealing, was sentenced to at least 15 years and two months at the Old Bailey for the murder of 18-year-old Stephen in 1993. David Norris, 35, was given a minimum of 14 years and three months for the murder, which the judge said was a "terrible and evil crime".

Mrs Lawrence told the newspaper: "There is a lot they can do. People take their lead from the Government. If the Prime Minister said 'this is what I'd like to see happen in our society' ... people will try to work towards that. At the moment I'm not sure exactly what they are doing around race."

Mrs Lawrence also expressed regrets that after the guilty verdicts no minister sent a letter "in recognition of what has been denied for so long", it adds.

While the police were failing to catch her son's murderers, they managed to stop his brother Stuart 20 times as a criminal suspect, the newspaper said. He said: "David Cameron has not sent my mum a letter saying sorry it has taken so long. It shows the stance of the Conservative government. I don't think they care at all."

A Downing Street spokesman said: "The Prime Minister has spoken on a number of occasions of his admiration for Doreen Lawrence. He recently paid tribute to Mrs Lawrence and her family for the great bravery they have shown and he believes that their tireless fight for justice has helped to change the country for the better. He also recently made clear that he believes that although things have changed for the better, there is still a problem with racism in this country and more work to be done to tackle it.

"The Government is currently developing a new action plan to tackle hate crime, building on one of the strongest legislative frameworks anywhere in the world to protect communities from hostility, violence and bigotry. Everyone should have the freedom to live their lives free from fear of targeted hostility or harassment on the grounds of a particular characteristic, including skin colour.

"In addition, we will publish shortly a new approach to the integration of local communities. This will recognise that integration works well in most places, most of the time, but that some communities face significant issues. It will replace past top-down, centralised policies with an approach which unlocks the talent and efforts of communities, public bodies and the private sector.

"The Government has also put in place a substantial programme of activity to promote social mobility amongst disadvantaged communities, including those from ethnic minorities. This work is underpinned by the new Equality Act, which represents some of the strongest equality rights in the world."